1. Field Of The Invention
This invention relates generally to connectors and more particularly to a novel connector for connecting hollow rectangular tubular members.
2. Description Of The Prior Art
Many different ideas and proposals have been made for connectors for connecting hollow rectangular tubular members. Such connectors are widely used to construct showcases, display cases, shelving, kiosks and the like and have a very wide use.
An early type of connector is shown in my U.S. Pat. No. 3,532,369 which used a block with posts extending therefrom and the rectangular tubular members were releasably secured to the posts. The posts had oppositely extending projections which were resiliently compressible. The essential feature of this invention was that the combined diameters of the post and the projections were less than the length of the diagonals of the tubular members and slightly greater than the perpendicular distance between opposite faces of the tubular member so that the post can be inserted into the tubular member and after axial rotation of the tubular member, the post effected a releasable interference fit between the projections and the inside of the tubular member.
That original connector was improved as shown in my U.S. Pat. No. 3,645,599 granted on Feb. 29, 1972 by using a vinyl insert between the tubular member and the spigot. A still further improvement is illustrated in my U.S. Pat. No. 3,666,298 which used a resiliently compressible plastic casing having longitudinal ribs corresponding in number to the number of sides of the tubular member. The casing is secured to the core so that there is no movement between the casing and the core.
Other devices may be seen in the prior art as illustrated in Canadian patent number 841,261 (dated May 12, 1970 to Peacock) U.S. Pat. No. 2,926,941 (Thompson) U.S. Pat. No. 3,232,160 (Fork et al) and others.
These prior art devices, while quite an improvement over the then existing prior art, have now become much more expensive particularly due to the increased cost of the vinyl or plastic inserts. Also, the costs have risen due to increased labour costs since the vinyl inserts must be manually inserted on the spigots and inspected to insure proper orientation and fit.